Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

The ultrafast heating of implosions using cone/shell geometeries was discussed. The study was carried out by using the 1054 nm, nanosecond, 0.9 kJ output of the VULCAN Nd:glass laser to drive 186 μm diameter, 6 μm wall thickness Cu-dopped deuterated plastic (CD) shells in 6-beam cubic symmetry. It was found that x-ray preheat, combined with lower ablation pressures, indicate that infrared drive was unlikely to be useful in full scale direct drive ignition design. The results show that the higher density of the compressed plasma promotes more collimated flow, but at the cost of reduced background heating.

Abstract:

Laser-plasma interaction experiments were conducted using the VULCAN laser at the Rutherford Appleton Laboratory. The consequence of the return current and measurements of proton generation from the wire targets interacting with short pulse high intensity laser were produced. Optical and x-ray emission from the wire due to Ohmic heating caused by the return current were observed and an m=0 instability was found to develop in the wires. The proton emission was found to be in the form of an almost uniform double disk perpendicular to the wire at the interaction region.

Abstract:

This paper presents an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. The theory is used to interpret x-ray scattering experiments from solid density carbon plasmas and to extract accurate measurements of electron temperature, electron density, and charge state. The experimental results are applied to validate various equation-of-state models for carbon plasmas. (C) 2004 American Institute of Physics.

Abstract:

The observations of proton emission from wire targets, performed at the Rutherford Appleton Laboratory were reported. The experiments were carried out by using the Chirped Pulsed Amplification beam line of VULCAN laser facility. It was observed that the presence of objects in the vicinity of the interaction had an effect on the angular emission pattern of protons from the primary targets. The results show that the objects in close proximity of the main target can become sheath formation on the secondary object.